Apparatus for promoting healing processes

ABSTRACT

An apparatus for promoting healing of body tissue composed of a coil arranged to be applied to the affected body part and to be connected to a low frequency a.c. source to produce a magnetic field within the region to be treated, and at least two sheetlike electrodes associated with the coil and spaced from one another, the electrodes being arranged to be located at respectively opposite sides of the region to be treated and to be connected to a source of a low frequency voltage to produce an electric field within the region to be treated at the same time as the magnetic field.

[76] Inventor: Werner Kraus, 31 Bauerstrasse,

Munich, Germany [22] Filed: Mar. 25, 1974 [21] Appl. No.: 454,557

[30] Foreign Application Priority Data Mar. 23, 1973 Germany 2314573[52] US. Cl. l28/l.5; 128/82.l; 128/419 F; 128/419 R [51] Int. Cl. A61N1/42 [58] Field of Search 128/1.5, 404, 405, 411, 128/419 PF, 419 R, 420A, 421, 422, 423, 82.1, 1 C

[56] References Cited UNITED STATES PATENTS 2,368,207 l/1945 Eaton128/422 2,404,283 7/1946 Gieringer 128/405 3,490,458 1/1970 Allison128/421 3,648,708 3/1972 Hoeri 128/422 FOREIGN PATENTS OR APPLICATIONS871,672 6/1961 United Kingdom 128/420 United States Patent 1191 [1113,915,151

Kraus Oct. 28, 1975 1 APPARATUS FOR PROMOTING HEALING 2,116,869 10/1971Germany 128/82.1

PROCESSES 1,109,280 6/1961 Germany 128/420 OTHER PUBLICATIONS Cochran,Bulletin of the New York Academy of Medicine" Vol. 48, No. 7, Aug. 1972,pp. 89991 1.

Primary Examiner-William E. Kamm Attorney, Agent, or FirmSpencer & Kaye[57] ABSTRACT An apparatus for promoting healing of body tissue composedof a coil arranged to be applied to the affected body part and to beconnected to a low frequency a.c. source to produce a magnetic fieldwithin the region to be treated, and at least two sheet-like electrodesassociated with the coil and spaced from one another, the electrodesbeing arranged to be located at respectively opposite sides of theregion to be treated and to be connected to a source of a low frequencyvoltage to produce an electric field within the region to be treated atthe same time as the magnetic field.

5 Claims, 7 Drawing Figures FUNCTION. GENERATOR FOR ELECTRIC ANDMAGNETIC FIELDS FUNCTION GENERATOR FOR ELECTRIC AND MAGNETIC FIELDSFIG.2

FUNCTION GENERATORX US. Patent Oct. 28, 1975 Sheet 2 of3 3,915,151

FUNCTION GENERATOR U.S. Patent Oct.28, 1975 Sheet 3-of3 3,915,151

PREAMPLI FIER VOLTAGE AMPLIFIER mm F APPARATUS FOR PROMOTING HEALINGPROCESSES BACKGROUND OF THE INVENTION The present invention relates toan apparatus for promoting healing processes of the type including acoil adapted to be applied to a part of the body to be treated and whichis adapted to be connected with a source for a varying current with alow frequency and makes it possible to produce a corresponding magneticfield, which pervades the part of the body to be treated.

The German Pat. Specification (Patentschrift) No. 1,918,299,corresponding to my US. Pat. No. 3,745,995, and the German PatentSpecification (Offenlegungsschrift) No. 2,1 15,869, corresponding to mypending US. application Ser. No. 241,727, filed April 6, 1972, and alsothe Munchner Medizinische Wochenschrift 42 (1972), pages 1814 to 1819refer to the promotion of healing of fractured bones by a low frequencyAC pervading the injured bone zone galvanically. The AC has preferably afrequency below 100 Hz and a curve form Without steep leading andtrailing flanks.

The AC prevading the injured bone Zone can be induced by an implantedreceiving coil, provided with corresponding electrodes, using a magneticfield, which is produced by a coil which is applied to the part of thebody to be treated and is connected with a suitable AC generator.

Furthermore, the above-mentioned German Pat. Specification No. 2,116,869 refers to the fact that the influence of a suitably directed lowfrequency magnetic alternating field alone leads to an encouragement ofhealing processes and to enhanced vascularisation (formation of bloodvessels).

SUMMARY OF THE INVENTION One aim of the present invention is that ofcreating an apparatus which makes possible a still more pronouncedencouragement of healing processes than the above-mentioned forms ofapparatus.

This aim is to be achieved in accordance with the invention by anapparatus of the above-mentioned type which is characterised in that thecoil is provided with two sheetlike electrodes which are arranged with aspacing between them and are adapted to be connected with a source oflow frequency varying voltage for the production of an electric fieldwhich pervades the part of the body to be treated simultaneously withthe magnetic field.

It has thus been found that the regeneration of damaged bone and softtissue can be substantially promoted by the simultaneous application ofslowly varying electricl and magnetic fields, preferably withapproximately the same strength.

The sheet-like electrodes are electrically insulated from the part ofthe body to be treated or are so arranged at a distance from it thatthrough the body part to be treated there flows no galvanic conductioncurrent and instead only the displacement and polarisation current flowsthrough the part of the body, this current being produced by theelectric field between the sheetlike electrodes arranged like the platesof a capacitor.

Further developments and forms of the invention are defined in thesubordinate claims.

An important feature of the invention resides in that the electric andmagnetic fields, preferably having approximately the same energycontent, vary with the same frequency but are shifted in phase relativeto each other, the phase shift being approximately about In whatfollows, embodiments of the invention will be described with referenceto the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a diagrammaticrepresentation of an apparatus in accordance with a first embodiment ofthe invention, which is especially suitable for treating extremities ofthe human body.

FIG. 2 is a diagrammatic representation of a second embodiment of theinvention.

FIG. 3a is a diagrammatic view of a third embodiment of the invention.

FIG. 3b shows an enlarged cross-section through a marrow pin belongingto the apparatus in accordance with FIG. 3a.

FIG. 4 shows a view similar to FIG. 3a of a further embodiment of theinvention.

FIGS. 5 and 6 show partly sectioned views of further embodiments of theinvention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The embodiment of the inventionshown in FIG. 1 comprises a substantially cylindrical coil 10 (solenoidcoil), which can be slid over the extremity, for example a leg 12indicated in broken lines, to be treated. On the inner wall of the coil10, on opposite sides, two electrodes 14 are arranged, which eachconsist for example of a thin metal sheet material, and are providedwith insulation, not shown, which prevents galvanic or conductivecontact between the electrodes 14 and the leg 12 to be treated, oranother part of the body. The coil 10 and the electrodes 14 areconnected respectively with wires 16, only indicated diagrammatically,leading to an electrical function generator 18, which supplies a currentfor the supply of the coil 10 and a voltage for supply of the electrodes14.

The current supplied to the coil 10 can be a symmetrical or asymmetricalAC or DC withsuperimposed AC components or it can be a pulsatingcurrent. The frequency of the AC or of the AC component of the coilcurrent produced by the function generator 18 is preferably adjustableand lies in the range of 1 to Hz for example and preferably betweenapproximately 5 and 30 Hz. The oscillation form of the AC or AC component respectively is preferably relatively low in harmonies (forexample less than 20% or 10% harmonics). The leading and trailing flanksof the AC half cycles should not be abrupt and instead should begradual. Therefore, in contrast to a sinusoidal or triangular wavecurrent a square wave current is undesired.

The function generator preferably comprises means for producing currentcharacteristics or functions which are copied from physiologicalvariations in the human body, for example the course of the movement ofthe ribs during breathing, the pressure characteristic or function inthe lungs or the course of the pulse wave form, and more particularlythe systol or a healthy, normal person.

Much the same applies for the voltage which is supplied by the functiongenerator 18 to the electrodes 14.

Electrical circuit arrangments for the supply of voltages and currentsof a complicated wave form are described in the book Waveforms RadiationLaboratory Series, McGRaw-Hill, New York, 1949 for example. Voltage andcurrent functions copied from physiological functions can be producedfor example by using suitably constructed sensors applied to the bodyand using amplifier circuits for the supply of the coils and electrodesrespectively with the required current strength or voltage respectively.Finally, also signals of the desired shape can be stored on a loop ofmagnetic tape, which is then played back with a suitable speed and theplayed back signals are amplified in the manner required for supply ofthe coil and the electrodes respectively.

The amplitudes of the AC current and voltage are preferably adjustableand preferably have such values that the energy content of the magneticfield pervading the part of the body treated and the energy content ofthe electric field simultaneously pervading the treatd part of the bodyare at least approximately the same. The magnetic field strength intissue can lie for example between 20 and 200 Gauss, while theelectrical field strength for the treatment of tissue regions close tothe electrodes can amount to approximately 0.1 V/cm to approximately 1V/cm. For the treatment of deeper regions or parts of the body it isalso possible to operate with substantially higher field strengths.

The function generator 18 can comprise setting members for simultaneousand independent variation of the amplitudes of the AC voltage and of theAC current.

Preferably the function generator 18 furthermore comprises a devicewhich makes it possible to adjust the phase position between the ACcurrent and the AC voltage. Preferably the AC current and the ACvoltagbe and, respectively, the AC current and the AC voltage componentsof the current supply to the coil and of the voltage applied to theelectrodes 14 have a phase shift of approximately 90.

The coil 10 and the electrodes 14 associated with it are preferably soconstructed that the magnetic field lines diagrammatically shown aresubstantially parallel to the principal direction of the flow of bloodin the part of the body treated or, respectively, in the longitudinaldirection of an extremity being treated. The electrical fields should,on the other hand, be approximately perpendicular to the magnetic fieldsand therefore be generally perpendicular to the physiologicalorientation, for example the direction of the fibers in the bone.

The device or apparatus in accordance with FIG. 1 is especially suitablefor encouraging the healing of closed bone fractures, in the case ofwhich the repositioning fixation of the parts of the fractured bone inrelation to each other) is not carried out by an operation and insteadis brought about by external fixing with plaster. In the case of suchfractures the duration of healing and therefore the danger of atrophicinterference, more particularly in the case of older persons, can besubstantially reduced.

FIG. 2 shows an embodiment of the invention with a magnetic coilarrangement 10, which comprises a number of flat coils 10a to 10f, whichcan be regarded as flattened cylinder coils and are connected, at theirlongitudinal edges running parallel to the axis of coiling,- with eachother in a jointed manner so that they can be applied for exampleexternally to the torso or head and then produce an axial magnetic fieldin the respective part of the body. The flat coils 10a to 10f areconnected electrically in series and are connected with a functiongenerator 18, as has been explained with reference to FIG. 1.

The side, facing in a certain direction, of each flat coil 10a to 10fcarries a corresponding plate-like electrode 14a to 14f, whose surfaceis provided with insulation coating which is not shown.

The electrodes, arranged on the flat coils 10a to 100, are connectedwith a lead connected with the function generator 18, while the otherlead connected with the function generator 18 is connected with theelectrodes of the flat coil 10d to 10f. The electric and magnetic fielddistribution occurring in this embodiment of the invention is shown inFIG. 2 the magnetic field lines being represented by long broken linesand the electric field lines being represented by short broken lines.

FIG. 3a shows in section a fractured bone 20, which has been reset bymeans of a marrow nail 22. The marrow nail 22 comprises a receiving coil24 (FIG. 3b) of a rodshaped ferrite core, on which a solenoid winding isarranged. In contrast to the above-mentioned known electro marrow nailsthe ends of the receiving coil 24 are, however, not connected with theelectrodes on the surface of the marrow nail, which are in galvaniccontact with the bone to be healed, and instead are connected withelectrodes 14, whose surfaces are insulated, so that no galvaniccurrents can flow between them. The electrodes 14 can be embedded forexample in the marrow nail, which at least for this part consists of adielectric material.

The marrow nail 22 described is mounted as is conventional in theinjured bone 20 and the injured extremity comprising the marrow nail 22with the receiving coil 24 is then brought into the field of a coil 10placed over the injured extremity. The coil 10 is connected with afunction generator 18 of the type described with reference to FIG. 1.The voltage induced by the magnetic field of the coil 10in the receivingcoil 24 passes to the insulated electrodes 14' so that in the bone zonean electrical field is produced which runs generally perpendicularly tothe magnetic field. The coil 10 can, as has been explained withreference to FIG. 1, additionally be provided with electrodes 14, whichare directly supplied with a voltage by the function generator 18 andthis voltage preferably has the same frequency as the AC in the coil 10,but with respect to this voltage is shifted in amplitude byapproximately In the case of the apparatus in accordance with FIG. 3 itis naturally also the magnetic field of the receiving coil 24 which iseffective, which can therefore be regarded as an equivalent to the coil10.

The apparatus in accordance with FIG. 4 is similiarly constructed to theapparatus in accordance with FIG. 3a and for components equivalent infunction the same reference numerals have been used. In the case of FIG.4 the fractured bone 20 is, however, not pinned or nailed and instead,since it is a question of a closed fracture, it is fixed by a plastercast or the like. In the plaster, insulated field electrodes 14 areembedded and are connected by flexible electrical leads with thefunction generator. Another possibility resides in providing windows ina plaster or plastic cast and fixing the field electrodes in the windowsacting as frames adjacent to the surface of the extremity to be treatedso that the electrodes are separated by an air gap from the surface ofthe patient. The coil and the electrodes 14 are supplied by a functiongenerator 18 with a low frequency current or a low frequency voltage.The function generator 18' is synchronised or controlled in the case ofthis embodiment by means of a pulse receiving means 30, that is to sayin the latter case the course of the AC or of the AC voltage correspondsto the pulse pressure wave. he function generator 18' can as analtemative measure also be synchronised by an electrocardiogram orcontrolled with respect to the curve shape.

In the case of the apparatus in accordance with FIG. 4 the pulsereceiving means can for example be a pressure sensor or a very lowfrequency microphone M and the function generator 18 can comprise thefollowing circuit units: A pre-amplifier, whose input is connected withthe pulse receiving means 30 and whose output is connected on the onehand directly with the input of a current amplifier and on the otherhand is connected with an adjustable phase shifting device forconnection with the input of a voltage amplifier. The output of thecurrent amplifier supplies the magnet coil 10, while the output of thevoltage amplifier is connected with the electrodes 14 it beingunderstood that in practice there are two output leads from the voltageamplifier rather than the one shown.

FIGS. 5 and 6 show two embodiments of the present device, which comprisea pin-like body 32 with rounded ends, which can consist of a fluorinecarbon polymer for example. In the body there is a substantiallycylindrical shaped receiving coil 24 which can comprise a rod-shapedmagnetic core which is not especially shown.

The ends of the receiving coil are connected respectively with twoelectrodes, which are embedded in the body 32. Preferably the surface ofeach electrode is insulated so that no galvanic currents can flow fromit. The electrodes 24a of the embodiment in accordance with FIG. 5 havethe shape of parts of the cylindrical casing and are arranged onopposite sides of the body 32. The electrodes 14b of the embodiment inaccordance with FIG. 6 are annular and arranged on the body 32 with anaxial spacing.

The embodiment in accordance with FIGS. 5 and 6 can be mounted in themarrow channel of a bone, for example in the case of osteomyelitis, andfurthermore they are suitable for producing autologous replacement offibers by growing round or encapsulation.

The present apparatus is particularly suitable for encouraging healingprocesses in and under closed skin, that is to say in the case of closedfractures and also in the case of pathological processes in tissue. Thepolarisation force of the electrical field has a substantial influenceon the recovery of the structure of the damaged tissue, while thedistribution of blood vessels within the structure is directlyinfluenced by the magnetic field. Owing to the combination of electricaland magnetic fields the essential conditions for regeneration of afunctioning structure, that is to say healing, are provided.

A further possiblity of influencing the biological processes in thetissues is based in the fact that the magnetic and/or electricalalternating field, more particularly the latter, can have DC componentssuperimposed on it, which may possibly be so large that no reversal ofpolarity of the field occurs and instead a pulsating field with apredetermined polarity comes into play. In

this case the function generator 18 or 18' respectively can comprisecircuitry features which make it possible to superimpose on the ACsupplied to the coil 10 DC preferably with adjustable amplitude and ifnecessary adjustable polarity and/or make it possible to superimpose onthe AC voltage supplied to the electrodes 14 a DC voltage, preferablywith an adjustable amplitude and polarity.

The preferred phase shift between electrical and magnetic fields can,however, also be produced by a delay member, possibly adjustable, in thefunction generator or also by a differentiating member, which derives ACvoltage from AC supplied to the coil 10, and whose course or shapecorresponds to the differential with respect to time of the AC current.The use of a differentiating member for the production of the desiredphase shift between the magnetic and electrical fields is particularlysuitable in the case of the use of nonsinusoidal current or voltageshapes or characteristics, for example when the course of the fields isto be adapted to a biological magnitude, for example the pulse pressurewave or systole.

What I claim is:

1. In apparatus for promoting healing processes and comprising a coiladapted to be applied to a part of the body to be treated and adapted tobe connected with a source for a varying current with a low frequencyfor causing the coil to produce a corresponding magnetic field in thelongitudinal direction of and which pervades the part of the body to betreated, the improvement comprising two sheet-like electrodes associatedwith said coil, disposed with a spacing between them and arranged to beconnected with a source of low frequency varying voltage of producing anelectric field which pervades the part of the body to be treatedsimultaneously with the magnetic field, said electrodes extending atleast approximately parallel to the surface occupied by the windings ofthe coil.

2. An apparatus in accordance with claim 1 wherein the coil is composedof a number of flat coils connected to each other in a jointed manner,with at least two of said coils being provided with a respective one ofsaid sheet-like electrodes.

3. An apparatus in accordance with claim 1 further comprising arod-shaped body of a tissue-compatible insulating material, and areceiving coil carried by said body, and wherein said two electrodes areelectrically connected to said receiving coil and extend adjacent to thesurface of said body.

4. An apparatus in accordance with claim 3 wherein said electrodes areprovided with an insulating surface.

5. In apparatus for promoting healing processes and comprising a coiladapted to be applied to a part of the body to be treated and adapted tobe connected with a source for a varying current with a low frequencyfor causing the coil to produce a corresponding magnetic field, whichpervades the part of the body to be treated, the improvement comprisingtwo insulated sheet-like electrodes, disposed with a spacing betweenthem and arranged to be connected with a source of low frequency varyingvoltage for producing an electric field which pervades the part of thebody to be treated simultaneously with the magnetic field, a bone splintimplantate member; a receiving coil arranged on such implantate memberand magnetically linked to said firstrecited coil, said receiving coilhaving terminals each connected to a respective one of said twoinsulated sheet-like electrodes and constituting said source of voltage.

1. In apparatus for promoting healing processes and comprising a coiladapted to be applied to a part of the body to be treated and adapted tobe connected with a source for a varying current with a low frequencyfor causing the coil to produce a corresponding magnetic field in thelongitudinal direction of and which pervades the part of the body to betreated, the improvement comprising two sheet-like electrodes associatedwith said coil, disposEd with a spacing between them and arranged to beconnected with a source of low frequency varying voltage for producingan electric field which pervades the part of the body to be treatedsimultaneously with the magnetic field, said electrodes extending atleast approximately parallel to the surface occupied by the windings ofthe coil.
 2. An apparatus in accordance with claim 1 wherein the coil iscomposed of a number of flat coils connected to each other in a jointedmanner, with at least two of said coils being provided with a respectiveone of said sheet-like electrodes.
 3. An apparatus in accordance withclaim 1 further comprising a rod-shaped body of a tissue-compatibleinsulating material, and a receiving coil carried by said body, andwherein said two electrodes are electrically connected to said receivingcoil and extend adjacent to the surface of said body.
 4. An apparatus inaccordance with claim 3 wherein said electrodes are provided with aninsulating surface.
 5. In apparatus for promoting healing processes andcomprising a coil adapted to be applied to a part of the body to betreated and adapted to be connected with a source for a varying currentwith a low frequency for causing the coil to produce a correspondingmagnetic field, which pervades the part of the body to be treated, theimprovement comprising two insulated sheet-like electrodes, disposedwith a spacing between them and arranged to be connected with a sourceof low frequency varying voltage for producing an electric field whichpervades the part of the body to be treated simultaneously with themagnetic field, a bone splint implantate member; a receiving coilarranged on such implantate member and magnetically linked to saidfirst-recited coil, said receiving coil having terminals each connectedto a respective one of said two insulated sheet-like electrodes andconstituting said source of voltage.